Question:
If one accidentally gave himself a paper cut on Shabbos, or otherwise accidentally caused himself to bleed, is that an aveira, or is it misaseik? Does one need to do teshvua?
Answer:
A person who desecrates the Shabbos by doing a melocha unintentionally e,g. falling against the wall and accidentally switching on the light is called misaseik. There is a dispute if misaseik is not considered a melocho at all (and therefore doesn't need teshuvah) or only a petur (exemption) from bringing a korban (and therefore would require teshuvah). Regarding Shabbos Reb Akivah Eiger says it is not considered a malocho because there you need "meleches machsheves".
Sources:
Rashi Bava Kama 26b & Sanhedrin 62b, Rambam Shegogos1:8, Teshuvas Reb Akivah Eiger 8, O:CH 301 Mishnah Berurah 19, 316:5 Biur Halachah ד"ה חייב
